IELTS Reading Practice Test 11: Free, with Answers

AFor most of history, the question of whether other stars have planets could only be answered by speculation. By the twentieth century, most astronomers assumed that planets were common. Yet there was no way of proving it. A planet does not produce light of its own but only reflects that of its star, which is typically millions or even billions of times brighter, and at the distance of even the nearest stars, the two would appear so close together that the planet would be lost in the glare. As recently as the early 1990s, not a single planet was known beyond our own solar system. Today more than 6,000 have been confirmed, and astronomers estimate that our galaxy contains more planets than stars.

BThe first confirmed discovery came from an unexpected direction. In 1992, the astronomers Aleksander Wolszczan and Dale Frail announced that they had found two planets orbiting a pulsar, the small, rapidly spinning remains of a star that had exploded. A pulsar emits beams of radio waves that sweep past the Earth with extraordinary regularity, and by timing these pulses with the giant radio telescope at Arecibo in Puerto Rico, the two men detected tiny irregularities which could only be explained by the pull of orbiting bodies. The discovery was a landmark, but it seemed to reveal little about planets like our own, since any world orbiting a pulsar would be exposed to intense radiation and could hardly support life.

CThe planet that transformed the field was announced three years later. In October 1995, Michel Mayor and Didier Queloz of the University of Geneva reported a planet orbiting 51 Pegasi, a star very similar to the Sun. They had used what is known as the radial velocity method. As a planet travels around its star, its gravity pulls the star back and forth very slightly, and this movement produces tiny shifts in the colour of the star's light, towards blue as the star approaches us and towards red as it moves away. The planet they detected astonished astronomers. It had about half the mass of Jupiter, yet it completed an orbit in just over four days, far closer to its star than Mercury is to the Sun. No theory had predicted that a giant planet could exist in such a position, and some scientists initially doubted whether the signal had been caused by a planet at all.

DA second technique soon proved even more productive. If a planet's orbit happens to be aligned so that it passes directly between its star and the Earth, it blocks a small fraction of the star's light, causing a slight dimming that is repeated with every orbit. In 1999, a team that included David Charbonneau observed this effect for the first time, as a planet crossed the face of a star known as HD 209458 and reduced its brightness by less than two per cent. The transit method, as it is called, has an important advantage: the depth of the dip reveals the size of the planet. When this is combined with radial velocity measurements, which indicate its mass, astronomers can calculate the planet's density and judge whether it is rocky, like the Earth, or made largely of gas.

EThe method was applied on a vast scale by the Kepler space telescope, launched by NASA in 2009. The mission was the idea of William Borucki, a scientist who had spent years arguing that a telescope in space could detect planets as small as the Earth, and whose proposals had been rejected several times before NASA finally agreed to fund it. For four years, Kepler stared at a single patch of sky, recording the brightness of around 150,000 stars at the same time. By the time it ran out of fuel in 2018, it had discovered more than 2,600 planets, and its data revealed that planets between the size of the Earth and that of Neptune are the most common of all, even though our own solar system contains none.

FDetecting a planet indirectly is one thing; seeing it is quite another. To photograph a planet beside its star, astronomers must block or remove the overwhelming starlight and correct for the blurring effect of the Earth's atmosphere. In 2008, a team led by Christian Marois published images of three planets orbiting the star HR 8799, the first picture of a family of planets around another star. This approach, known as direct imaging, works best for large, young planets which are still hot from their formation and orbit far from their stars, so it complements the other methods rather than replacing them.

GThe next challenge is to study the atmospheres of these distant worlds. When a planet passes in front of its star, a little of the starlight filters through its atmosphere, and the gases there absorb particular wavelengths, leaving a kind of chemical fingerprint in the light that reaches us. In 2022, the James Webb Space Telescope used this technique to detect carbon dioxide in the atmosphere of a giant planet, the first clear detection of the gas beyond our solar system. Astronomers hope that future instruments will be able to examine the atmospheres of rocky planets for combinations of gases, such as oxygen and methane, that might be produced by living organisms. Possible signs of this kind have already been reported, but so far none has been confirmed.

Around 1940, an American fire-insurance inspector named Benjamin Lee Whorf published a series of essays arguing that the language people speak shapes the way they think. Whorf had noticed during his inspections that workers behaved carelessly around petrol drums described as ‘empty’, even smoking beside them, although drums that had held fuel were filled with explosive vapour and were in fact more dangerous than full ones. The word ‘empty’, he suggested, led the workers to think of the drums as harmless. From observations of this kind, and from his study of Native American languages, Whorf developed a far bolder claim: that speakers of very different languages live, in effect, in different mental worlds.

The idea, which became known as the Sapir-Whorf hypothesis after Whorf and his teacher Edward Sapir, was enormously influential for a time, but it rested on weak foundations. Whorf's best-known example was the Hopi language of Arizona, which, he claimed, contained no words or grammatical forms referring to time as English speakers understand it. In 1983, however, the linguist Ekkehart Malotki published a study of almost 700 pages documenting the many ways in which Hopi does express time. The popular belief that the Inuit have hundreds of words for snow fared no better. The anthropologist Franz Boas had mentioned four in 1911, but in later retellings the number grew to dozens and eventually hundreds, while specialists pointed out that English, too, has many words for snow, from sleet to slush. By the 1990s, many researchers regarded the whole idea as discredited. In a best-selling book, the psychologist Steven Pinker dismissed it as ‘wrong, all wrong’, arguing that people think in a mental language of their own, which exists independently of the words they speak.

In recent decades, however, the question has been reopened, this time with experiments rather than anecdotes. One striking case concerns languages that do not use words such as ‘left’ and ‘right’ to describe where objects are. Speakers of Guugu Yimithirr, an Aboriginal language of north-eastern Australia, describe locations in terms of compass directions, saying, for instance, that a cup is to the north of a plate. To speak in this way, they must know which way they are facing at every moment, and research by the anthropologist John Haviland and the linguist Stephen Levinson found that they do, keeping track of their orientation with remarkable accuracy even in unfamiliar places. When shown a row of objects on a table and then turned around to face the opposite direction, speakers of languages like this tend to rebuild the row according to the compass, whereas Dutch and English speakers preserve its order relative to their own bodies.

Colour provides another example. Russian, unlike English, has two separate basic words for blue: goluboy for lighter shades and siniy for darker ones. In a study published in 2007, Russian speakers were quicker to tell two shades of blue apart when the shades fell on opposite sides of this boundary than when both had the same name, while English speakers showed no such difference. The advantage disappeared when participants were asked to repeat a string of numbers silently while performing the task, which suggests that language was involved in the act of seeing itself, rather than simply in describing afterwards what had been seen.

Not every finding has survived closer examination, however. A widely reported experiment from the early 2000s suggested that grammatical gender affects how objects are imagined: German speakers, for whom the word for ‘bridge’ is feminine, were said to describe bridges as beautiful and elegant, whereas Spanish speakers, for whom it is masculine, chose words such as strong and sturdy. When a team of German researchers tried to reproduce the effect in 2014, they found no trace of it, and a later attempt to repeat the Russian colour study did not fully confirm its findings. Such failures are a reminder that effects which make memorable stories are not necessarily large or reliable.

What, then, should we conclude? In my view, the evidence rules out the strong version of Whorf's claim. There is no sign that a language traps its speakers inside a particular view of the world or makes certain thoughts impossible. Indeed, if languages created entirely separate worlds, translation would be impossible, and yet people translate between them every day. It would be equally mistaken, however, to conclude that language has no influence at all. The more modest claim, that the habits of a particular language direct attention towards some features of experience and away from others, is now well supported. The linguist Roman Jakobson expressed this neatly when he observed that languages differ essentially in what they must convey, not in what they may convey. A speaker of Guugu Yimithirr cannot say where a cup is without knowing where north is, and over a lifetime, that obligation trains the mind.

Numbers may be the clearest case of all. The Pirahã people of the Amazon have no words for exact numbers: their terms for small quantities mean roughly ‘one’, roughly ‘two’ and ‘many’. In experiments reported in 2004, Pirahã adults struggled to match sets of more than three objects precisely, although they were able to estimate larger quantities approximately. This does not mean that the Pirahã cannot learn to count. Rather, it suggests that number words act as a kind of tool, which allows people to hold exact large quantities in mind. Seen in this light, language is less like a prison than like a toolkit. It does not determine what we are able to think, but it makes some kinds of thinking easier, quicker and more natural than others, and that, I would argue, is influence enough to make the question worth asking.